the largest yeast collection of general character in Slovakia, is located in the Institute of Chemistry, Slovak Academy of Sciences in Bratislava. It is a member of European Culture Collections' Organization (ECCO) as well as the World Federation of Culture Collections (WFCC). The CCY collection holds 3,600 strains of yeasts and yeast-like organisms including biotechnologically important strains, strains isolated from different contaminated sources, from various ecological niches, strains with specific characteristics, mutant cultures, type and patent strains. The collection has been regularly enriched by the fresh isolates and the other industrially and scientifically interesting strains (www.natur.cuni.cz/fccm).

The CCY is a sole collection in Slovakia authorized for deposition of patent yeast strains and has acquired the status of International Depositary Authority under the Budapest Treaty on the International Recognition of the Deposit of Microorganisms for the Purposes of Patent Procedure as from August 31, 1992.

The biotechnology, food, and pharmaceutical industries have had a long and profitable association with the yeasts. Their traditional applications include the formation of important products such as bread, wine, beer, sparkling alcoholic drinks, distilled drinks, etc., the result of specific fermentations carried out by certain strains of primarily Saccharomyces sp. Industrial yeasts are becoming more and more significant nowadays. More recently, a wider range of yeast species have found application in biotransformation, bioremediation, chiral compound production, flavour production, the fats and oils industry, pharmaceutical screens, and protein production. The development in genetics and molecular biology have opened up the possibility of the genetic manipulation of yeasts for commercial purposes.

Microbial cultures are the cornerstone of microbiology and they are held in culture collections. These collections represent the known microbial diversity which is conserved under genetically stable conditions for the use of present and future generations of scientists.

The research activities of CCY are mainly directed to:

• Identification of new isolates
• Study of properties of different strains
• Improvement of preservation methods
• Studies on ecology of yeasts and yeast-like organisms

• Supply of cultures
• Isolation of yeasts from nature and contaminated materials
• Identification and characterization of strains
• Deposit of patent cultures including that according to the Budapest Treaty

Almost all yeast strains are subcultured on slant agar media and stored either in a refrigerator at a temperature about 4 °C or covered with paraffin oil and stored at room temperature. This method has some disadvantages - i.e. after prolonged subculturing the risk of selection and adaptation to the cultivation medium arise and changes or losses of important properties could occur.

Insufficiency of the classical storage method is not found in the cryopreservation. In our collection the procedure for the cryoprotection was elaborated. It guarantees high survival rate and it is, therefore, very suitable mainly for biotechnologically important strains, because risk of selection and adaptation are reduced to a minimum.

Head of CCY: R. Vadkertiová, PhD; e-mail: chemvad@savba.sk

Deputy of head of CCY: E. Breierová, PhD; e-mail: chememi@savba.sk